Service request handling

ABSTRACT

Embodiments here in relate to methods for message handling performed by an Access and Mobility Management function, AMF, and a User Equipment, UE, as well as a corresponding AMF and UE. Particularly, embodiments herein relate to methods for handling service requests performed by an Access and Mobility Management function, AMF, and a User Equipment, UE, as well as a corresponding AMF and UE.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application No.17/577,092 filed on Jan. 17, 2022, which is a continuation of U.S. Pat.Application No. 16/319,039 filed on Jan. 18, 2019, which is a 35 U.S.C.§ 371 national stage application of PCT International Application No.PCT/EP2018/050432 filed on Jan. 9, 2018, which in turns claims domesticpriority to U.S. Provisional Pat. Application No. 62/443,979, filed onJan. 9, 2017, the disclosures and content of which are incorporated byreference herein in their entireties.

TECHNICAL FIELD

Disclosed are embodiments for handling service requests.

BACKGROUND

The Third Generation Partnership Project (3GPP) has begun on work on thedevelopment and design of the next generation mobile communicationssystem (a.k.a., the 5G mobile communication system or the NextGeneration (NG) system or simply “5G” or “NG” for short). In the 3GPPNexGen study phase it is concluded that the Mobility Management (MM)function and the Session Management (SM) function (SMF) shall beseparated. See, e.g., 3GPP TR 23.799 v14.0.0 (2016-12). The MM function(MMF) is also known as the Access and Mobility Management function(AMF), accordingly the AMF and the MMF are equivalent.

SUMMARY

Due to the separation of the AMF and SMF and the single NAS terminationin the AMF in 5G, the 5G Service Request (SR) procedure handling isdifferent than the 3G and 4G SR procedure handling. This disclosureaddresses the following issues with respect to the 5G SR procedurehandling: (1) user plane (UP) setup latency; (2) efficient NAS signalingfor total PDU session synchronization between user equipment (UE) andnetwork; and (3) utilization of common logic for Mobile Terminated (MT)traffic and Mobile Originated (MO) traffic handling.

The UP setup latency in the SR procedure can be improved because it isnot necessary to bundle the UP setup for all PDU sessions in one SRprocedure.

For example, in one embodiment, when a User Equipment (UE) (i.e., adevice capable of wireless communication, such as, for example, asmartphone, a tablet, a personal computer, a utility meter, a sensor, avending machine, etc.) initiates a NAS SR indicating a set of one ormore PDU sessions needed for UP re-established (i.e., a set of one ormore PDU sessions that require UP resources, such as, for example, dataradio bearers and related UP tunnels) and requesting individual answers(e.g. UP setup from network) per PDU session, each implicated SMFhandles UP setup (or failure handling of UP setup) individually for eachPDU session and the AMF shall only wait for the first PDU UP setupbefore continuing the NG2 setup, the other PDU sessions are handledasynchronously toward NG2 (and NG1) by the AMF. In another embodiment,the AMF concatenates several PDU sessions for UP setup based on a timebudget, e.g., AMF may optionally collect the SMF responses for thedifferent PDU sessions and use one response back to the UE/Radio AccessNetwork (RAN) within a time period determined by the time budget.

For the “total PDU session” status synch between the UE and network(i.e. synch the UE view of PDU sessions previously established with thenetwork view of the previously established PDU sessions), a NAS logic isintroduced and used only when total PDU session status is notsynchronized (i.e. when the UE view is different than the network view).

Additionally, in some embodiments, when the UE initiates an SR procedurein response to paging that was triggered due to MT traffic, the UEindicates the corresponding PDU session(s) for which UP resources areneeded (in addition to indicating the corresponding PDU session the UEmay indicate another PDU session for which the UE has uplink data tosend to the network). Accordingly, in one embodiment, the AMF includesthe corresponding PDU session ID (e.g., a simplified representation) inNG2 Paging Request, and the UE shall use this information to indicate inan SR message the PDU sessions requested for UP re-establishment for MTtraffic (as noted above, the SR message may further include informationindicating other PDU sessions as well — e.g., PDU sessions for which theUE has uplink data to send).

In other embodiments, when the UE initiates an SR procedure in responseto a page that was triggered due to MT traffic, the UE does not indicatethe corresponding PDU session(s) for which UP is needed. Rather, theAMF, based on information that it stored when it received the datanotification from the SMF that triggered the page, obtains the PDUsession ID and transmits to the SMF that sent the notification an NG11SM notification request.

Advantages provided by embodiments disclosed herein include: (1) UPsetup latency for different PDU sessions is decoupled, which isbeneficial for the individual service latency, and enables also networkslice isolation; (2) an efficient PDU session status synchronizationbetween UE and network (in current 3G, Service accept is always neededin PMM-Connected mode and in 4G no Service Accept and always using lowerlayer as response); and (3) enabling of efficient service re-activationwhere both UE and network needs are catered for in a common way.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate various embodiments.

FIG. 1 illustrates an exemplary Next Generation communication structure.

FIG. 2 is a message flow diagram illustrating a process according to oneembodiment.

FIG. 3 is a message flow diagram illustrating a process according to oneembodiment.

FIG. 4 is a flow chart illustrating a process according to oneembodiment.

FIG. 5 is a flow chart illustrating a process according to oneembodiment.

FIG. 6 is a flow chart illustrating a process according to oneembodiment.

FIG. 7 is a block diagram of an AMF according to some embodiments.

FIG. 8 is a block diagram of a UE according to some embodiments.

FIG. 9 is a flow chart illustrating a process according to oneembodiment.

FIG. 10 is a diagram showing functional modules of an AMF according tosome embodiments.

FIG. 11 is a flow chart illustrating a process according to oneembodiment.

FIG. 12 is a diagram showing functional modules of a UE according tosome embodiments.

FIG. 13 is a flow chart illustrating a process according to oneembodiment.

FIG. 14 is a diagram showing functional modules of an AMF according tosome embodiments.

DETAILED DESCRIPTION

As mentioned above, the AMF and SMF are separated in the 5G corenetwork. Referring now to FIG. 1 , FIG. 1 illustrates an exemplary 5Gcommunication system 100. The 5G communication system 100 illustrates apoint to point reference point representation.

As shown in FIG. 1 , a single NG1 interface is used for both MM andSM-related messages and procedures for a UE 102. The single NG1termination point is located in the AMF 104.

The AMF 104 and SMF 106 are separate NFs (Network Function), with astandard NG11 interface specified in-between. AMF 104 handles themobility management part of NAS signalling exchanged with UE 102, andthe SMF 106 handles the session management part of NAS signallingexchanged with UE 102.

UE 102 may have multiple established PDU sessions and may be served bydifferent instances of SMF 106. The AMF 104 selects the SMF functionsfor the PDU sessions. AMF may select different SMF functions fordifferent PDU sessions.

AMF forwards session management (SM) related NAS information to the SMF.

Upon successful PDU session establishment, AMF stores the identificationof serving SMFs of UE (e.g., for each established PDU session, the AMFstores information for linking a PDU session ID that identifies the PDUsession with an SMF ID that identifies the SMF handling the identifiedPDU session — e.g., the AMF may store a record having a first field thatstores the PDU session ID and a second field that stores the SMF ID),and SMF stores the identification of serving AMF of UE. The AMF is notexpected to maintain any additional session context information. The AMFis not required to be aware of the content of SM NAS messages.

In case of UE having multiple established PDU sessions using multipleuser plane (UP) functions (UPFs), the 5G system supports the independentactivation of UE-CN UP connection per PDU session. The following MM andSM interactions are envisaged: (1) during transition from IDLE toCONNECTED state, for MT data transmission the “Impacts of MM events”procedure is used, and for MO data transmission the UE indicates duringthe Service Request procedure the PDU session(s) for which the UE-CN UPconnection has to be activated; (2) when UE is in CONNECTED state,during mobility procedures (e.g. handover) within a AMF updates only theSMFs for which the UE has active UE-CN UP connection(s); and (3) duringCONNECTED state, if the UE has activated UE-CN UP connection for asubset of active PDU sessions, NG system supports the activation ofadditional UE-CN UP connection for further PDU sessions.

Some NG2 signalling (such as Hand-Over related signalling) may requirethe action of both AMF and SMF. In such case, the AMF is responsible toensure the coordination between AMF and SMF. This may correspond tofollowing procedures: (A) NG2 impacts of SM events and (B) Impacts of MMevents.

NG2 impacts of SM events procedure includes: (1) At the set-up /modification / release of a PDU session and UE-CN UP connectionactivation/deactivation: the SMF interacts with RAN via the AMF forsetup, modification and release of radio and NG3 resources for the PDUsession; and (2) At the set-up/modification of QoS for GBR flows ormodification of QoS rules for non-GBR flows, the SMF interacts with theRAN via the AMF to provide the QoS information.

Impacts of MM events procedure includes: (1) at the transition from IDLEto CONNECTED: the SMF, for which the UE-CN UP connection(s) is to beactivated, interacts with RAN via the AMF for setting up of radio andNG3 resources for the PDU session.

As mentioned above, due to the separation of the AMF and SMF, and thesingle NAS termination in the AMF in 5G, the Service Request (SR)procedure handling is handled differently from 3G and 4G. According tothe different 5G SR procedure the following issues are addressed: (1) UPsetup latency in the SR procedure; (2) efficient NAS signaling for totalPDU session synchronization between user equipment (UE) and network; and(3) utilization of common logic in the SR procedure for MobileTerminated (MT) traffic and Mobile Originated (MO) traffic handling.

FIG. 2 is a flow chart illustrating a process, according to oneembodiment, for establishing (e.g., re-establishing) a UP (i.e., settingup resources) for enabling the UE to send uplink data to a UP function(UPF).

When the UE has data to send to the UPF, the UE transmits a servicerequest (SR) (e.g., an NG1 Service Request) comprising information(e.g., a first parameter) indicating the UE’s PDU sessions that requireUP establishment (step 201). For example, the SR may include a firstordered set of N bits (i.e., a “bitmap”)), where each one of the N bitscorresponds to a different one of N possible PDU sessions that couldrequire UP establishment (e.g., the first bit in the string correspondsto a first PDU session, the second bit in the string corresponds to asecond PDU session, etc.). In some embodiments, N is equal to the totalnumber of PDU sessions that are deemed active by the UE (e.g., N=3),whereas in other embodiments N is equal to the total number of possibleactive PDU sessions in the UE (e.g., N=16). The value of each bit in thebit string indicates whether the PDU session corresponding to the bitrequires UP establishment (e.g. if bit n is set to a value of 1, thenthe PDU session #n is requires UP establishment, but if the bit n is setto a value of 0, then the PDU session #n does not require UPestablishment). In this way, the UE can signal to the network the UPstatus of each active PDU session for the UE.

Upon receiving the SR, the AMF examines the information (e.g., thebitmap) included in the SR to determine the PDU sessions for which UPresources are to be established and further examines stored informationthat maps PDU sessions to SMFs to determine, for each PDU session forwhich the UP is to be established, the SMF that is handling the PDUsession (it is possible that a single SMF is handling multiple PDUsessions for the UE). After identifying the SMFs that are handling thePDU sessions for which UP is to be established, the AMF transmits toeach one of the identified SMFs an NG11 message (a notification orrequest) (step 203).

In some embodiments, the SR transmitted by the UE further includes PDUsession status information (e.g., a second parameter) that identifies,for each possible PDU session, the status of the PDU session (e.g.,active or inactive). For example, the SR may include a second bitmap ofN bits, where each one of the N bits corresponds to a different one of Npossible PDU sessions (e.g., the first bit in the string corresponds toPDU session #1, the second bit in the string corresponds to PDU session#2, etc.). The value of each bit in the bit string indicates the statusof the PDU session corresponding to the bit (e.g. if bit n is set to avalue of 1, then the PDU session #n is active but if the bit n is set toa value of 0, then the PDU session #n is inactive). In this way, the UEcan signal to the network the status of each possible PDU session forthe UE.

In one embodiment, upon receipt of the SR, the AMF checks for anydifferences between the PDU session status information included in theSR (e.g., indicated by the second bitmap) and PDU sessions statusinformation previously stored by the AMF. For example, the AMF itselfmay store for each UE that it serves a bitmap containing informationregarding the status of the UE’s PDU sessions. In step 201 a, the AMFmay send an NG1 response (e.g., an NAS response) to the UE tosynchronize the PDU session status information if there areunsynchronized PDU sessions (i.e., if the PDU session status informationincluded in the SR does not match the PDU session status informationmaintained by the AMF). That is, step 201 a may be performed if there isa mismatch between the PDU session status indicated in the SR sent bythe UE and the PDU session status information for the UE that ismaintained by the AMF, which mismatch implies the need forsynchronization. As a specific example, if the UE sends an SR containingthe bitmap “0000 0000 0011 0000,” this means that the UE has indicatedto the network that PDU sessions 5 and 6 are active. If the PDU sessionstatus information for the UE that is maintained by AMF also indicatesthat PDU sessions 5 and 6 are active, then it’s fine. If, however, thePDU session status information for the UE that is maintained by AMFindicates only that PDU session 5 is active, then the AMF can indicateback to UE with a bitmap of 0000 0000 0001 0000. This will indicate tothe UE that the UE should inactive PDU session 6.

In an embodiment, the UE may start a timer to monitor the response(s)from the RAN.

In response to the NG11 messages, each SMF responds to AMF individuallywith an NG11 response (steps 204 a-c). The NG11 responses include an NG2SM container (i.e., a block of information) which may include corenetwork (CN) UP tunnel information and quality of service (QoS)information for the PDU session. The NG11 responses can be successful orunsuccessful.

In step 205 a, upon receipt of the first NG11 response from an SMF(e.g., SMF1) (step 204 a) the AMF generates an NG2 MM containercomprising, among other information, information regarding AS security,and transmits the NG2 MM container along with the received NG2 SMcontainer to the RAN without waiting for responses from the other SMFs.For example, in step 204 a, without waiting for any other responses fromthe other SMFs to which the AMF sent the NG11 notification, the AMFtransmits to the RAN an NG2 message (e.g., context setup) that comprisesthe NG2 SM container and the NG2 MM container.

In an embodiment, NG2 MM container comprises an NG1 response (e.g., theNAS response) when there is the above described PDU session stateinformation mismatch has been detected by the AMF.

In steps 205 b-c, the NG11 responses from SMF2 and SMF3 (see steps 204 band 204 c) are transmitted by the AMF to the RAN and UE, respectively.That is, in step 205 b, the AMF transmits to the RAN an NG2 messagecomprising the NG2 SM container received from SMF2 in step 204 b, and instep 205 c, the AMF transmits to the UE a NAS message in response toreceiving the NG11 response in step 204 c. In this example, the AMFtransmits to the UE a NAS message in response to receiving the NG11response in step 204 c because the NG11 response received in step 204 cindicates that the SMF3 lost the PDU session and missed asynchronization with the AMF (i.e., the SMF3 may respond directly to theUE with a NG1 Response (e.g., NAS Response)).

In some embodiments, rather than send to the RAN the NG2 message (e.g.,context setup) immediately after receiving the first NG11 response(i.e., without waiting for any responses from the other SMFs to whichthe AMF sent the NG11 notification), the AMF, based on a time budget,may include several NG2 SM containers in one NG2 message. The timebudget can be based on a predetermined configuration or policy. In anembodiment, the time budget can be based on the learning of thecriticality of the application and/or service in the PDU session. Forinstance, the AMF may activate a timer to expire after X seconds (X isthe time budget) and when the timer expires the AMF may transmit to theRAN the NG2 message, which NG2 message will contain the NG2 MM containerand each one of the NG2 SM containers received by the AMF prior to theexpiration of the timer. The AMF may activate the timer immediatelyafter transmitting the first NG11 notification or it may activate thetimer immediately after receiving the first NG11 response.

In step 206, the RAN transmits an NG2 context setup response to setupthe UPs for each PDU session individually. The NG2 context setupresponse comprises the NG2 SM container and information regarding theaccess network (AN) UP tunnel. In an embodiment, the UE takes furtheractions based on the response time measured by the timer to monitor theresponse(s) from the RAN. In cases where the AMF includes two or moreNG2 SM containers (e.g., from different SMFs) in the NG2 message sent tothe RAN, the RAN may send only one NG2 response that includes acorresponding two or more NG2 containers (at NG2 and N11 interface, ifthe requesting node sends several items in one request, the receivingnode shall respond with several corresponding items in one response),and, for each NG2 container included in the NG2 response, the AMFtransmits the NG2 container to the appropriate SMF.

In step 207, the AMF forwards the NG2 context setup responses, whichincludes the radio access network through an NG11 request to theappropriate SMFs.

FIG. 3 is a message flow diagram illustrating a process, according tosome embodiments, to re-establish UP from UE to the network for the MTdata triggered paging and service request.

In step 301, UPF 112 receives downlink (DL) UP data for UE 102.

In step 302, UPF 112 sends to SMF 106 a DL UP data notification messageto notify SMF 106 that UPF 112 has received DL UP data for UE 102.

In step 303, SMF 106 sends to AMF 104 a UP setup request.

In step 304, determines whether the UE is in the CN-IDLE mode and, ifso, the AMF triggers a paging of the UE (i.e., triggers the sending of apaging message to the UE). In one embodiment, AMF 104 includes in thepaging message sent to the UE PDU session identification information foridentifying the PDU session for which the UP is being established (i.e.,information for identifying which PDU session has MT data). In someembodiments, the AMF determines the PDU session identificationinformation based on the SMF from which the AMF received the UP setuprequest. For example, in some embodiments, the AMF may store contextinformation for UEs that it serves, which context information mayinclude information mapping a PDU session identifier to an SMFidentifier.

In step 305, in response to receiving the paging message, the UEperforms an SR procedure (transmits an SR to the AMF). The SR, asdiscussed above, may include information (e.g., the above describedsecond bitmap) that identifies, for each possible PDU session, thestatus of the PDU session. Additionally, if the AMF included in thepaging message PDU session identification information identifying one ormore PDU sessions having DL UP data for the UE, then the UE may furtherinclude in the SR PDU session identification information for identifyingthe PDU session(s) identified in the paging message (e.g., the PDUsession identification information may be the above described firstbitmap). Moreover, if the UE has uplink (UL) UP traffic on other PDUsessions at the same time the UE received the paging message, then theUE may also include in the SR information indicating that these otherPDU sessions need UP establishment (e.g., if the UE as UL UP data on PDUsession #3, then the UE may set to a value of 1 the bit in the firstbitmap that corresponds to PDU session #3).

The rest of the procedure is similar to the UE triggered service requestflow, as illustrated in FIG. 2 .

In another embodiment, the AMF does not include the PDU sessionidentification information in the paging message sent to the UE. Rather,the AMF may correlate the SMF/PDU sessions when an SR is received fromUE based on the UE identifier.

For example, when the AMF receives from the SMF a request indicating aPDU session (e.g. PDU Session #1) for a particular UE and furtherindicating an SMF ID (e.g., SMF-ID 1), the AMF may store in a database(e.g., a file) a record having a first field that contains a UEidentifier for identifying the particular UE, a second field storinginformation identifying the PDU session, and a third field storing theSMF ID. Thus, when the AMF receives the SR from the UE, which SRincludes the UE’s ID, the AMF can use the UE’s ID to retrieve the recordfrom the database and then obtain the PDU session ID and SMF ID from therecord. Once the AMF has obtained the PDU session ID and SMF ID from therecord, the AMF can now send to the SMF identified by the SMF ID an NG11message (e.g., a notification comprising the PDU session ID). If thedatabase includes more than one record with the same UE ID in the UE IDfield, then the AMF can send an appropriate NG11 message to each one ofthe identified SMFs.

FIG. 4 is a flow chart illustrating a process 400, according to oneembodiment, that is performed by the AMF for message handling (e.g.,service request handling).

Process 400 may begin with step 402 in which the AMF receives a firstmessage (e.g., a service request) transmitted by the UE, wherein thefirst message comprises information (e.g., a first bitmap) identifying:i) a first PDU session for which a UP is to be established and ii) asecond PDU session for which a UP is to be established.

In step 404, the AMF identifies a first SMF that is associated with thefirst PDU session.

In step 406, the AMF identifies a second SMF that is associated with thesecond PDU session.

In step 408, as a result of identifying the first SMF, the AMF transmitsto the first SMF a second message (e.g., an NG11 notification/request).

In step 410, as a result of identifying the second SMF, the AMFtransmits to the second SMF a third message (e.g., an NG11notification/request).

In step 412, the AMF receives a response transmitted by the first SMF inresponse to the second message, wherein the response transmitted by thefirst SMF comprises a first session management (SM) container (i.e., aset of SM information) for an access node (108) serving the UE.

In step 414, immediately after receiving the response transmitted by thefirst SMF (i.e., without waiting for any response from the second SMF),the AMF transmits to the access node a message. The message comprises a)a mobility management (MM) container and b) the first SM containerreceived from the first SMF.

In some embodiment, after transmitting to the access node the messagecomprising a) the mobility management (MM) container and b) the first SMcontainer received from the first SMF, the AMF receives a responsetransmitted by the access node. The response transmitted by the accessnode comprises radio access network (RAN) UP information for the firstSMF. Upon receipt of the response transmitted by the access node, theAMF forwards the RAN UP information to the first SMF. The RAN UPinformation enables the first SMF to communicate the RAN UP informationto a UP function (UPF) for the first PDU session.

In some embodiment, the first SM container comprises informationindicating a first core network (CN) UP tunnel and a first quality ofservice (QoS).

In some embodiments, process 400 further includes steps 416 and 418.

In step 416, after transmitting the message to the access node, the AMFreceives a response transmitted by the second SMF in response to thethird message. The response transmitted by the second SMF comprises asecond SM container for the access node serving the UE.

In step 418, after receiving the response transmitted by the second SMF,the AMF transmits to the access node a message comprising the second SMcontainer received from the second SMF.

In some embodiment, after transmitting to the access node the messagecomprising the second SM container received from the second SMF, the AMFreceives a response transmitted by the access node. The responsetransmitted by the access node comprises radio access network (RAN) UPinformation for the second SMF. Upon receipt of the response transmittedby the access node, the AMF forwards the RAN UP information to thesecond SMF. The RAN UP information enables the second SMF to communicatethe RAN UP information to a UP function (UPF) for the second PDUsession.

In some embodiment, the second SM container comprises informationindicating a second CN UP tunnel and a second QoS.

FIG. 5 is a flow chart illustrating a process 500, according to oneembodiment, that is performed by the AMF for message handling (e.g.,service request handling).

Process 500 may begin with step 502 in which the AMF receives a firstmessage (e.g., a service request) transmitted by the UE, wherein thefirst message comprises information (e.g., a first bitmap) identifying:i) a first PDU session for which a UP is to be established and ii) asecond PDU session for which a UP is to be established.

In step 504, the AMF identifies a first session managing function (SMF)that is associated with the first PDU session.

In step 506, the AMF identifies a second SMF that is associated with thesecond PDU session.

In step 508, as a result of identifying the first SMF, the AMF transmitsto the first SMF a second message (e.g., an NG11 notification/request).

In step 510, as a result of identifying the second SMF, the AMFtransmits to the second SMF a third message (e.g., an NG11notification/request).

In step 512, the AMF sets a timer. The AMF may also initialize a counter(e.g., set i=0) for keeping track of the number of SMF responses the AMFreceives. In an embodiment, the timer is set based on predeterminedconfigurations and policies. In another embodiment, the timer is setbased on a level of criticality of application and service in the firstPDU session and the second PDU session.

In step 514, the AMF determines whether it has received a response toone of the messages transmitted in steps 508 and 510. If no response hasbeen received, the process 500 proceeds to step 522, otherwise when aresponse is received the process 500 proceeds to step 516.

In step 516, which is reached when the AMF receives a response to one ofthe messages sent in steps 508 and 510, the AMF increments the counter(e.g., calculates i = i + 1). The received response (e.g., a responsetransmitted by the first or second SMF) comprises a session management(SM) container for an access node serving the UE.

In step 518, the AMF determines whether i equals a variable N, wherein Nindicates the number of SMFs from which a response can be received. If i= N, the process 500 proceeds to step 519 (i.e., all expected responseshave been received), otherwise the process 500 proceeds to step 522. Inthis embodiment, N = 2 because a response can be received from the firstand the second SMFs. In another embodiment, N can be any number inaccordance with the number of SMFs a response can be received from.

In step 519, the AMF deactivates the timer.

In step 522, the AMF determines whether the timer has expired. If thetimer has not expired, the process 500 returns to step 514, otherwisethe process 500 proceeds to step 524.

In step 524, the AMF determines whether i = 0. If i = 0, the process 500proceeds to step 526, otherwise the process 500 proceeds to step 520.

In step 526, the AMF indicates an error.

In step 520, the AMF transmits to the access node a message. The messagetransmitted in step 520 includes, for each SMF response received by thispoint in time, the SM container included in the response. For example,it is possible that the AMF receives only one SMF response (e.g., aresponse transmitted by the first SMF). In such a scenario, the AMFtransmits to the access node a message comprising a) a mobilitymanagement (MM) container and b) the SM container received from thefirst SMF. As another example, it is possible that, before the timeexpires, the AMF receives a first response transmitted by the first SMFand also receives a second response transmitted by the second SMF, wherethe first response comprises a first SM container and the secondresponse comprises a second SM container. In such a scenario, in step520 the message transmitted by the AMF to the access node will include:a) a mobility management (MM) container, b) the first SM containerreceived from the first SMF, and c) the second SM container receivedfrom the second SMF.

In some embodiments of method 400 and/or 500, the first message furthercomprises PDU session status information (e.g., a second bitmap) thatidentifies, for each possible PDU session, the status of the PDUsession. In such embodiment, the method may further include: retrievingpreviously stored PDU session status information for the UE; determiningwhether the PDU session status formation contained in the first messagematches the retrieved PDU status information for the UE; and in responseto determining that the PDU session status formation contained in thefirst message does not match the retrieved PDU status information forthe UE, transmitting to the UE a PDU session status synchronizationmessage (e.g., an NG1 message) to synchronize the PDU session statusinformation.

FIG. 6 is a flow chart illustrating a process 600, according to oneembodiment, that is performed by the AMF for message handling (e.g.,service request handling).

The process 600 may begin with step 602, in which the AMF receives afirst message (e.g., an NG11 request) transmitted by a session managingfunction (SMF) in response to the SMF receiving a notification thatdownlink (DL) data for a user equipment (UE) has been received. The UEhas at least one PDU session, the DL data is associated with aparticular one of the UE’s PDU sessions, and the first message comprisesinformation indicating a request to setup a UP.

In step 604, in response to receiving the first message, the AMFtransmits via an access node a paging message to the UE, wherein thepaging message comprises information indicating said particular one ofthe UE’s PDU sessions.

FIG. 7 is a block diagram of AMF 104 according to some embodiments. Asshown in FIG. 7 , the AMF 104 may comprise: a data processing system(DPS) 702, which may include one or more processors 755 (e.g., a generalpurpose microprocessor and/or one or more other processors, such as anapplication specific integrated circuit (ASIC), field-programmable gatearrays (FPGAs), and the like); network interface 705 for use inconnecting AMF to a network such that AMF 102 can communicate with theother described functions (e.g., SMF) and RAN 108; and local storageunit (a.k.a., “data storage system”) 712, which may include one or morenon-volatile storage devices and/or one or more volatile storage devices(e.g., random access memory (RAM)). In embodiments where the AMF 104includes a general purpose microprocessor, a computer program product(CPP) 741 may be provided. CPP 741 includes a computer readable medium(CRM) 742 storing a computer program (CP) 743 comprising computerreadable instructions (CRI) 744. CRM 742 may be a non-transitorycomputer readable medium, such as, but not limited, to magnetic media(e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g.,random access memory), and the like. In some embodiments, the CRI 744 ofcomputer program 743 is configured such that when executed by dataprocessing system 702, the CRI causes the AMF to perform steps describedabove (e.g., steps described above with reference to the flow charts).In other embodiments, the AMF may be configured to perform stepsdescribed herein without the need for code. That is, for example, dataprocessing system 702 may consist merely of one or more ASICs. Hence,the features of the embodiments described herein may be implemented inhardware and/or software.

FIG. 8 is a block diagram of a UE 102 according to some embodiments. Asshown in FIG. 8 , UE 102 may comprise: a data processing system (DPS)802, which may include one or more processors 855 (e.g., a generalpurpose microprocessor and/or one or more other processors, such as anapplication specific integrated circuit (ASIC), field-programmable gatearrays (FPGAs), and the like); a radio transmitter 805 and a radioreceiver 806 coupled to an antenna 822 for use in wirelesslycommunicating with a radio access network (RAN) node (e.g., a TRP); andlocal storage unit (a.k.a., “data storage system”) 812, which mayinclude one or more non-volatile storage devices and/or one or morevolatile storage devices (e.g., random access memory (RAM)). Inembodiments where UE 102 includes a general purpose microprocessor, acomputer program product (CPP) 841 may be provided. CPP 841 includes acomputer readable medium (CRM) 842 storing a computer program (CP) 843comprising computer readable instructions (CRI) 844. CRM 842 may be anon-transitory computer readable medium, such as, but not limited, tomagnetic media (e.g., a hard disk), optical media (e.g., a DVD), memorydevices (e.g., random access memory), and the like. In some embodiments,the CRI 844 of computer program 843 is configured such that whenexecuted by data processing system 802, the CRI causes UE 102 to performsteps described above (e.g., steps described above with reference to theflow charts). In other embodiments, UE 102 may be configured to performsteps described herein without the need for code. That is, for example,data processing system 802 may consist merely of one or more ASICs.Hence, the features of the embodiments described herein may beimplemented in hardware and/or software.

Concise description of various disclosed embodiments

I. Mobile Originated (MO) Service Request Handling

A1. A method (400) performed by an AMF (104) for message handling (e.g.,service request handling), comprising:

-   receiving (402) a first message (e.g., a service request)    transmitted by a user equipment, UE (102), wherein the first message    comprises information (e.g., a first bitmap) identifying: i) a first    PDU session for which a UP is to be established and ii) a second PDU    session for which a UP is to be established;-   identifying (404) a first SMF that is associated with the first PDU    session;-   identifying (406) a second SMF that is associated with the second    PDU session;-   as a result of identifying (404) the first SMF, transmitting (408)    to the first SMF a second message (e.g., an NG11    notification/request);-   as a result of identifying (406) the second SMF, transmitting (410)    to the second SMF a third message (e.g., an NG11    notification/request);-   receiving (412) a response transmitted by the first SMF in response    to the second message, wherein the response transmitted by the first    SMF comprises a first session management (SM) container for an    access node (108) serving the UE; and-   immediately after receiving the response transmitted by the first    SMF, transmitting (414) to the access node a message comprising a) a    mobility management (MM) container and b) the first SM container    received from the first SMF.

A2. The method (400) of embodiment A1, further comprising:

-   after transmitting (414) the message to the access node, receiving    (416) a response transmitted by the second SMF in response to the    third message, wherein the response transmitted by the second SMF    comprises a second session management (SM) container for the access    node (108) serving the UE (102); and-   after receiving (416) the response transmitted by the second SMF,    transmitting (418) to the access node (102) a message comprising the    second SM container received from the second SMF.

A3. The method (400) of embodiment A1 or A2, wherein the first messagefurther comprises PDU session status information (e.g., a second bitmap)that identifies, for each possible PDU session, the status of the PDUsession.

A4. The method (400) of embodiment A3, further comprising:

-   retrieving previously stored PDU session status information for the    UE (102);-   determining whether the PDU session status formation contained in    the first message matches the retrieved PDU status information for    the UE (102).

A5. The method (400) of embodiment A4, further comprising:

in response to determining that the PDU session status formationcontained in the first message does not match the retrieved PDU statusinformation for the UE (102), transmitting to the UE (102) a PDU sessionstatus synchronization message (e.g., an NG1 message) to synchronize thePDU session status information.

A6. The method (400) of embodiment A1-A5, further comprising:

after transmitting to the access node the message comprising a) themobility management (MM) container and b) the first SM containerreceived from the first SMF, receiving a response transmitted by theaccess node (108), wherein the response transmitted by the access node(108) comprises radio access network (RAN) UP information for the firstSMF.

A7. The method (400) of embodiment A6, further comprising:

forwarding the RAN UP information to the first SMF, wherein the RAN UPinformation enables the first SMF to communicate the RAN UP informationto a UP function (UPF) for the first PDU session.

A8. The method (400) of any one of embodiments A2-A7, furthercomprising:

after transmitting to the access node (108) the message comprising thesecond SM container received from the second SMF, receiving a responsetransmitted by the access node (108), wherein the response transmittedby the access node (108) comprises radio access network (RAN) UPinformation for the second SMF.

A9. The method (400) of embodiment A8, further comprising:

forwarding the RAN UP information to the second SMF, wherein the RAN UPinformation enables the second SMF to communicate the RAN UP informationto a UP function (UPF) for the second PDU session.

A10. The method (400) of any one of the above embodiments, wherein

the information in the SR that identifiers the first and second PDUsessions for which a UP is to be established comprises a bitmapcomprising at least a first bit corresponding to the first PDU sessionand a second bit corresponding to the second PDU session.

A11. The method (400) of any one of the above embodiments, wherein thefirst SM container comprises information indicating a first core network(CN) user plane (UP) tunnel and a first quality of service (QoS), and

wherein the second SM container comprises information indicating asecond CN UP tunnel and a second QoS.

B1. An AMF (104) for message handling (e.g., service request handling),the AMF (104) adapted to:

-   receive (402) a first message (e.g., a service request) transmitted    by a user equipment, UE (102), wherein the first message comprises    information (e.g., a first bitmap) identifying: i) a first PDU    session for which a UP is to be established and ii) a second PDU    session for which a UP is to be established;-   identify (404) a first SMF that is associated with the first PDU    session;-   identify (406) a second SMF that is associated with the second PDU    session;-   as a result of identifying (404) the first SMF, transmit (408) to    the first SMF a second message (e.g., an NG11 notification/request);-   as a result of identifying (406) the second SMF, transmit (410) to    the second SMF a third message (e.g., an NG11 notification/request);-   receive (412) a response transmitted by the first SMF in response to    the second message, wherein the response transmitted by the first    SMF comprises a first session management (SM) container for an    access node (108) serving the UE (102); and-   immediately after receiving the response transmitted by the first    SMF, transmit (414) to the access node (108) a message comprising a)    a mobility management (MM) container and b) the first SM container    received from the first SMF.

C1. An AMF (104) for message handling (e.g., service request handling),the AMF (104) comprising:

-   a first obtaining module (1002) configured to obtain via a receiver    a first message (e.g., a service request) transmitted by a user    equipment, UE (102), wherein the first message comprises information    (e.g., a first bitmap) identifying: i) a first PDU session for which    a UP is to be established and ii) a second PDU session for which a    UP is to be established;-   a first identifying module (1004) for identifying a first SMF that    is associated with the first PDU session;-   a second identifying module (1006) configured to identify a second    SMF that is associated with the second PDU session;-   a first transmitting module (1008) configured to employ a    transmitter to transmit to the first SMF a second message (e.g., an    NG11 notification/request) as a result of identifying the first SMF;-   a second transmitting module (1010) configured to employ the    transmitter to transmit to the second SMF a third message (e.g., an    NG11 notification/request) as a result of identifying the second    SMF;-   a second obtaining module (1012) configured to obtain via the    receiver a response transmitted by the first SMF in response to the    second message, wherein the response transmitted by the first SMF    comprises a first session management (SM) container for an access    node (108) serving the UE (102); and-   a third transmitting module (1014) configured to, immediately after    obtaining the response transmitted by the first SMF, employ the    transmitter to transmit to the access node (108) the third message    comprising a) a mobility management (MM) container and b) the first    SM container received from the first SMF.

B/C2a. The AMF (104) of embodiment B1, being further adapted to:

-   after transmitting (414) the message to the access node, receive    (416) a response transmitted by the second SMF in response to the    third message, wherein the response transmitted by the second SMF    comprises a second session management (SM) container for the access    node (108) serving the UE (102); and-   after receiving (416) the response transmitted by the second SMF,    transmit (418) to the access node (108) a message comprising the    second SM container received from the second SMF.

B/C2b. The AMF (104) of embodiment C1, further comprising:

-   after employing the transmitter to transmit the message to the    access node, a third obtaining module (1018) configured to obtain    via the receiver a response transmitted by the second SMF in    response to the third message, wherein the response transmitted by    the second SMF comprises a second session management (SM) container    for the access node (108) serving the UE (102); and-   after obtaining via the receiver the response transmitted by the    second SMF, a fourth transmitting module (1020) configured to employ    the transmitter to transmit to the access node (108) a message    comprising the second SM container received from the second SMF.

B/C3. The AMF (104) of any one of the above AMF embodiments, wherein thefirst message further comprises PDU session status information (e.g., asecond bitmap) that identifies, for each possible PDU session, thestatus of the PDU session.

B/C4. The AMF (104) of embodiment B/C3, wherein

-   the AMF (104) is further adapted to: retrieve previously stored PDU    session status information for the UE (102); and determine whether    the PDU session status formation contained in the first message    matches the retrieved PDU status information for the UE (102); or-   the AMF (104) further comprises: a first retrieving module (1022)    configured to retrieve previously stored PDU session status    information for the UE (102); and a first determining module (1024)    configured to determine whether the PDU session status formation    contained in the first message matches the retrieved PDU status    information for the UE (102).

B/C5. The AMF of embodiment B/C4, wherein

-   the AMF (104) is further adapted to transmit to the UE (102) a PDU    session status synchronization message (e.g., an NG1 message) to    synchronize the PDU session status information in response to    determining that the PDU session status formation contained in the    first message does not match the retrieved PDU status information    for the UE (102); or-   the AMF (104) further comprises a fifth transmitting module (1028)    configured to, in response to determining that the PDU session    status formation contained in the first message does not match the    retrieved PDU status information for the UE (102), employ the    transmitter to transmit to the UE (102) a PDU session status    synchronization message (e.g., an NG1 message) to synchronize the    PDU session status information.

B/C6. The AMF (104) of any one of the above AMF embodiments, wherein theAMF (104) is further adapted to:

-   after transmitting to the access node the message comprising a) the    mobility management (MM) container and b) the first SM container    received from the first SMF, receive a response transmitted by the    access node, wherein the response transmitted by the access node    comprises radio access network (RAN) UP information for the first    SMF.

B/C7. The AMF (104) of embodiment B/C6, wherein the AMF (104) is furtheradapted to:

-   forward the RAN UP information to the first SMF, wherein the RAN UP    information enables the first SMF to communicate the RAN UP    information to a UP function (UPF) for the first PDU session.

B/C8. The AMF (104) of any one of the above AMF embodiments, wherein theAMF (104) is further adapted to:

-   after transmitting to the access node (108) the message comprising    the second SM container received from the second SMF, receive a    response transmitted by the access node (108), wherein the response    transmitted by the access node (108) comprises radio access network    (RAN) UP information for the second SMF.

B/C9. The AMF (104) of embodiment B/C8, wherein the AMF (104) is furtheradapted to:

-   forward the RAN UP information to the second SMF, wherein the RAN UP    information enables the second SMF to communicate the RAN UP    information to a UP function (UPF) for the second PDU session.

B/C10. The AMF (104) of any one of the above AMF embodiments, wherein

-   the information in the SR that identifiers the first and second PDU    sessions for which a UP is to be established comprises a bitmap    comprising at least a first bit corresponding to the first PDU    session and a second bit corresponding to the second PDU session.

B/C11. The AMF (104) of any one of the above AMF embodiments, whereinthe first SM container comprises information indicating a first corenetwork (CN) user plane (UP) tunnel and a first quality of service(QoS), and

-   wherein the second SM container comprises information indicating a    second CN UP tunnel and a second QoS.

D1. A method (500) performed by an AMF (104) for message handling (e.g.,service request handling), comprising:

-   receiving (502) a first message (e.g., a service request)    transmitted by a user equipment, UE (102), wherein the first message    comprises information (e.g., a first bitmap) identifying: i) a first    PDU session for which a UP is to be established and ii) a second PDU    session for which a UP is to be established;-   identifying (504) a first SMF that is associated with the first PDU    session;-   identifying (506) a second SMF that is associated with the second    PDU session;-   as a result of identifying (504) the first SMF, transmitting (508)    to the first SMF a second message (e.g., an NG11    notification/request);-   as a result of identifying (506) the second SMF, transmitting (510)    to the second SMF a third message (e.g., an NG11    notification/request);-   setting (512) a timer;-   receiving (514) a response transmitted by the first SMF in response    to the second message, wherein the response transmitted by the first    SMF comprises a first session management (SM) container for an    access node (108) serving the UE (102); and-   when the timer expires, transmitting (520) to the access node (108)    a message comprising a) a mobility management (MM) container and b)    the first SM container received from the first SMF.

D2. The method (500) of embodiment D1, the method (500) furthercomprising:

-   prior to when the timer expires, receiving a response transmitted by    the second SMF in response to the third message, wherein the    response transmitted by the second SMF comprises a second session    management (SM) container for the access node (108) serving the UE    (102); and-   when the timer expires, transmitting to the access node (108) a    message comprising a) a mobility management (MM) container, b) the    first SM container received from the first SMF, and c) the second SM    container received from the second SMF.

D3. The method (500) of embodiment D1 or D2, wherein the timer is setbased on predetermined configurations and policies.

D4. The method (500) of any one of embodiments D1 to D3, wherein thetimer is set based on a level of criticality of application and servicein the first PDU session and the second PDU session.

D5. The method (500) of any one of embodiments D1-D4, wherein the firstmessage further comprises PDU session status information (e.g., a secondbitmap) that identifies, for each possible PDU session, the status ofthe PDU session.

D6. The method (500) of embodiment D5, further comprising:

-   retrieving previously stored PDU session status information for the    UE (102);-   determining whether the PDU session status formation contained in    the first message matches the retrieved PDU status information for    the UE (102).

D7. The method (500) of embodiment D6, further comprising:

-   in response to determining that the PDU session status formation    contained in the first message does not match the retrieved PDU    status information for the UE (102), transmitting to the UE (102) a    PDU session status synchronization message (e.g., an NG1 message) to    synchronize the PDU session status information.

D8. The method (500) of any one of the embodiments D1-D7, wherein

-   the information in the SR that identifiers the first and second PDU    sessions for which a UP is to be established comprises a bitmap    comprising at least a first bit corresponding to the first PDU    session and a second bit corresponding to the second PDU session.

E1. An AMF (104) for message handling (e.g., service request handling),the AMF (104) adapted to:

-   receive (502) a first message (e.g., a service request) transmitted    by a user equipment, UE (102), wherein the first message comprises    information (e.g., a first bitmap) identifying: i) a first PDU    session for which a UP is to be established and ii) a second PDU    session for which a UP is to be established;-   identify (504) a first SMF that is associated with the first PDU    session;-   identify (506) a second SMF that is associated with the second PDU    session;-   as a result of identifying (504) the first SMF, transmit (508) to    the first SMF a second message (e.g., an NG11 notification/request);-   as a result of identifying (506) the second SMF, transmit (510) to    the second SMF a third message (e.g., an NG11 notification/request);-   set (512) a timer;-   receive (514) a response transmitted by the first SMF in response to    the second message, wherein the response transmitted by the first    SMF comprises a first session management (SM) container for an    access node (108) serving the UE (102); and-   when the timer expires, transmit (520) to the access node (108) a    message comprising a) a mobility management (MM) container and b)    the first SM container received from the first SMF.

F1. An AMF (104) for message handling (e.g., service request handling),the AMF (104) comprising:

-   a first obtaining module (1002) configured to obtain via a receiver    a first message (e.g., a service request) transmitted by a user    equipment, UE (102), wherein the first message comprises information    (e.g., a first bitmap) identifying: i) a first PDU session for which    a UP is to be established and ii) a second PDU session for which a    UP is to be established;-   a first identifying module (1004) configured to identify a first    session managing function (SMF) that is associated with the first    PDU session;-   a second identifying module (1006) configured to identify a second    SMF that is associated with the second PDU session;-   a first transmitting module (1008) configured to employ a    transmitter to transmit, as a result of identifying the first SMF,    to the first SMF a second message (e.g., an NG11    notification/request);-   a second transmitting module (1010) configured to employ a    transmitter to transmit, as a result of identifying the second SMF,    to the second SMF a third message (e.g., an NG11    notification/request);-   a first setting module (1016) configured to set a timer;-   a second obtaining module (1012) configured to obtain via the    receiver a response transmitted by the first SMF in response to the    second message, wherein the response transmitted by the first SMF    comprises a first session management (SM) container for an access    node (108) serving the UE (102); and-   a third transmitting module (1014) configured to employ a    transmitter to transmit, when the timer expires, to the access node    (108) a message comprising a) a mobility management (MM) container    and b) the first SM container received from the first SMF.

E/F2. The AMF (104) of embodiment E1 or F1, the AMF (104) furtheradapted to:

-   prior to when the timer expires, receive a response transmitted by    the second SMF in response to the third message, wherein the    response transmitted by the second SMF comprises a second session    management (SM) container for the access node (108) serving the UE    (102); and-   when the timer expires, transmit to the access node (108) a message    comprising a) a mobility management (MM) container, b) the first SM    container received from the first SMF, and c) the second SM    container received from the second SMF.

E/F3. The AMF (104) of embodiments E1-E2 or F1-F2, wherein the timer isset based on predetermined configurations and policies.

E/F4. The AMF (104) of embodiments E1-E2 or F1-F2, wherein the timer isset based on a level of criticality of application and service in thefirst PDU session and the second PDU session.

II. Mobile Terminated (MT) Service Request

G1. A method (600) performed by an AMF (104) for message handling (e.g.,service request handling), comprising:

-   receiving (602) a first message (e.g., an NG11 request) transmitted    by a SMF in response to the SMF receiving a notification that DL    data for a user equipment, UE (102), has been received, wherein the    UE (102) has at least one PDU session, the DL data is associated    with a particular one of the UE’s (102) PDU sessions, and the first    message comprises information indicating a request to setup a UP;    and-   in response to receiving (602) the first message, transmitting (108)    via an access node (108) a paging message to the UE (102), wherein    the paging message comprises information indicating said particular    one of the UE’s (102) PDU sessions.

H1. An AMF (104) for message handling (e.g., service request handling),the AMF (104) adapted to:

-   receive (602) a first message (e.g., an NG11 request) transmitted by    a session managing function (SMF) in response to the SMF receiving a    notification that downlink (DL) data for a user equipment, UE (102),    has been received, wherein the UE (102) has at least one PDU    session, the DL data is associated with a particular one of the UE’s    (102) PDU sessions, and the first message comprises information    indicating a request to setup a user plane (UP); and-   in response to receiving (602) the first message, transmit (604) via    an access node (108) a paging message to the UE (102), wherein the    paging message comprises information indicating said particular one    of the UE’s (102) PDU sessions.

I1. An AMF (104) for message handling (e.g., service request handling),the AMF (104) comprising:

-   a first obtaining module (1002) configured to obtain via receiver a    first message (e.g., an NG11 request) transmitted by a session    managing function (SMF) in response to the SMF receiving a    notification that downlink (DL) data for a user equipment, UE (102),    has been received, wherein the UE (102) has at least one PDU    session, the DL data is associated with a particular one of the UE’s    (102) PDU sessions, and the first message comprises information    indicating a request to setup a user plane (UP); and-   a first transmitting module (1008) configured to employ a    transmitter to transmit, in response to obtaining the first message,    via an access node (108) a paging message to the UE (102), wherein    the paging message comprises information indicating said particular    one of the UE’s (102) PDU sessions.

J1. A method (1100) performed by an AMF (104) for message handling(e.g., service request handling), comprising:

-   receiving (1102) a first message (e.g., an NG11 request) transmitted    by an SMF in response to the SMF receiving a notification that DL    data for a user equipment, UE (102), has been received, wherein the    UE (102) has at least one PDU session, the DL data is associated    with a particular one of the UE’s (102) PDU sessions, and the first    message comprises information indicating a request to setup a UP;    and-   in response to receiving (1102) the first message:-   storing (1104) a record comprising: i) an SMF identifier for    identifying the SMF and ii) a PDU session identifier for identifying    the particular PDU session, wherein the record is mapped to a UE    identifier for identifying the UE (102); and-   transmitting (1106) via an access node (108) a paging message to the    UE (102), wherein the paging message does not include information    indicating said particular one of the UE’s (102) PDU sessions.

J2. The method (1100) of embodiment J1, further comprising:

-   receiving an SR transmitted by the UE (102); and-   in response to receiving the SR:-   using the UE identifier to retrieve the stored SMF identifier and    PDU session identifier; and-   after retrieving the identifiers, transmitting to the SMF identified    by the SMF identifier a message (e.g., an NG11 message comprising    the PDU session identifier).

K1. An AMF (104) being adapted to:

-   receive (1102) a first message (e.g., an NG11 request) transmitted    by an SMF in response to the SMF receiving a notification that DL    data for a user equipment, UE (102), has been received, wherein the    UE (102) has at least one PDU session, the DL data is associated    with a particular one of the UE’s (102) PDU sessions, and the first    message comprises information indicating a request to setup a UP;    and-   in response to receiving (1102) the first message:-   store (1104) a record comprising: i) an SMF identifier for    identifying the SMF and ii) a PDU session identifier for identifying    the particular PDU session, wherein the record is mapped to a UE    identifier for identifying the UE (102); and-   transmit (1106) via an access node (108) a paging message to the UE    (102), wherein the paging message does not include information    indicating said particular one of the UE’s (102) PDU sessions.

K2. The AMF (104) of embodiment K1, wherein the AMF (104) is furtheradapted to:

-   receive an SR transmitted by the UE (102); and-   in response to receiving the SR:-   use the UE identifier to retrieve the stored SMF identifier and PDU    session identifier; and-   after retrieving the identifiers, transmit to the SMF identified by    the SMF identifier a message (e.g., an NG11 message comprising the    PDU session identifier).

L1. An AMF (104) comprising:

-   a first obtaining module (1002) configured to obtain via a receiver    a first message (e.g., an NG11 request) transmitted by an SMF in    response to the SMF receiving a notification that DL data for a UE    (102) has been received, wherein the UE (102) has at least one PDU    session, the DL data is associated with a particular one of the UE’s    (102) PDU sessions, and the first message comprises information    indicating a request to setup a UP; and-   in response to obtaining the first message:-   a first storing module (1026) configured to store a record    comprising: i) an SMF identifier for identifying the SMF and ii) a    PDU session identifier for identifying the particular PDU session,    wherein the record is mapped to a UE identifier for identifying the    UE; and-   a first transmitting module (1008) configured to employ a    transmitter to transmit via an access node (108) a paging message to    the UE (102), wherein the paging message does not include    information indicating said particular one of the UE’s (102) PDU    sessions.

L2. The AMF (104) of embodiment L1, further comprising:

-   a second obtaining module (1012) configured to obtain via the    receiver an SR transmitted by the UE (102); and-   in response to obtaining the SR:-   a first retrieving module (1022) configured to retrieve the stored    SMF identifier and PDU session identifier using the UE identifier;    and-   a second transmitting module (1010) configured to employ the    transmitter to transmit to the SMF identified by the SMF identifier    a message (e.g., an NG11 message comprising the PDU session    identifier) after retrieving the identifiers.

III. UE Embodiments

M1. A method (900, see FIG. 9 ) performed by a user equipment, UE (102),comprising:

-   determining (902) a first PDU session for which a UP is to be    established;-   generating (904) an SR; and-   transmitting (906) the SR to an AMF, wherein-   generating the SR comprises including in the SR information    indicating that the determined first PDU session is a PDU session    for which a UP is to be established.

M2. The method (900) of embodiment M1, wherein determining the PDUsession for which the UP is to be established comprises: receiving apaging message comprising PDU session identification information foridentifying the first PDU session and obtaining from the paging messagethe PDU session identification information.

M3. The method (900) of embodiment M2, further comprising:

-   determining a second PDU session for which a UP is to be    established, wherein-   generating the SR further comprises including in the SR information    indicating that the determined second PDU session is a PDU session    for which a UP is to be established.

M4. The method (900) of embodiment M3, wherein determining the secondPDU session comprises determining a PDU session for which the UE (102)has UL UP data to send to a recipient.

M5. The method (900) of embodiment M1, wherein determining the first PDUsession comprises determining a PDU session for which the UE (102) hasUL UP data to send to a recipient.

M6. The method (900) of embodiment M5, wherein including in the SRinformation indicating that the determined first PDU session is a PDUsession for which a UP is to be established comprises including a bitmapin the SR, wherein one of the bits of the bitmap corresponds to thefirst PDU session and said bit corresponding to the first PDU session isset to a value of 1.

N1. A user equipment (102), UE, the UE (102) being adapted to:

-   determine a first PDU session for which a UP is to be established;-   generate an SR; and-   transmit the SR to an AMF, wherein-   the UE is adapted to generate the SR by performing a process    comprising including in the SR information indicating that the    determined first PDU session is a PDU session for which a UP is to    be established.

O1. A user equipment (102), UE, the UE (102) comprising:

-   a determining module (1202) for determining a first PDU session for    which a UP is to be established;-   an SR generating module (1204) for generating an SR; and-   an SR transmitting module (1206) for employing a transmitter to    transmit the SR to an AMF, wherein-   the SR generating module is configured to generate the SR by    performing a process comprising including in the SR information    indicating that the determined first PDU session is a PDU session    for which a UP is to be established.

IV. PDU Session Status Synchronization

P1. A method (1300) for PDU session synchronization, comprising:

-   receiving (1302) a message transmitted by a UE (102), the message    comprising PDU session status information (e.g., a bitmap)    identifying a set of one or more PDU sessions deemed active by the    UE;-   in response to receiving the message, retrieving (1304) previously    stored PDU session status information for the UE;-   determining (1306) whether the PDU session status formation    contained in the received message matches the retrieved PDU status    information for the UE; and-   in response to determining that the PDU session status formation    contained in the received message does not match the retrieved PDU    status information for the UE, transmitting (1308) to the UE a PDU    session status synchronization message (e.g., an NG1 message) to    synchronize the PDU session status information.

P2. The method of embodiment P1, wherein the PDU session statussynchronization message comprises the previously stored PDU sessionstatus information for the UE.

P3. The method of embodiment P1 or P2, wherein the PDU session statussynchronization message comprises information instructing the UE todeactivate a PDU session that is included in the set of PDU sessiondeemed active by the UE.

Q1. An AMF (104) for PDU session synchronization, the AMF being adaptedto:

-   receive a message transmitted by a UE (102), the message comprising    PDU session status information (e.g., a bitmap) identifying a set of    one or more PDU sessions deemed active by the UE;-   retrieve previously stored PDU session status information for the UE    in response to receiving the message;-   determine whether the PDU session status formation contained in the    received message matches the retrieved PDU status information for    the UE; and-   transmit to the UE a PDU session status synchronization message    (e.g., an NG1 message) to synchronize the PDU session status    information in response to determining that the PDU session status    formation contained in the received message does not match the    retrieved PDU status information for the UE.

R1. An AMF (104) for PDU session synchronization, the AMF comprising:

-   an obtaining module (1402) for obtaining PDU session status    information (e.g., a bitmap) transmitted by a UE (102), the PDU    status information identifying a set of one or more PDU sessions    deemed active by the UE;-   a retrieving module (1403) adapted to retrieve previously stored PDU    session status information for the UE in response to receiving the    message;-   a determining module (1404) adapted to determine whether the PDU    session status formation contained in the received message matches    the retrieved PDU status information for the UE; and-   a PDU session status synchronization module (1406) adapted to employ    a transmitter to transmit to the UE a PDU session status    synchronization message (e.g., an NG1 message) in response to    determining that the PDU session status formation transmitted by the    UE does not match the retrieved PDU status information for the UE.

While various embodiments of the present disclosure are describedherein, it should be understood that they have been presented by way ofexample only, and not limitation. Thus, the breadth and scope of thepresent disclosure should not be limited by any of the above-describedexemplary embodiments. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by thedisclosure unless otherwise indicated herein or otherwise clearlycontradicted by context.

Additionally, while the processes described above and illustrated in thedrawings are shown as a sequence of steps, this was done solely for thesake of illustration. Accordingly, it is contemplated that some stepsmay be added, some steps may be omitted, the order of the steps may bere-arranged, and some steps may be performed in parallel.

Abbreviations

AMF Access and Mobility Management function CN Core Network DL DownLinkMM mobility management PDU Protocol Data Unit QoS Quality of Service RANRadio Access Network SM Session management SMF Session Managementfunction SR Service Request UE User Equipment, UP User Plane UPF UserPlane Function

1. A method performed by a user equipment, UE, comprising: determining aplurality of Protocol Data Unit, PDU, sessions for which a User Plane,UP, is to be established; transmitting a Non Access Stratum (NAS)Service Request (SR) to an Access and Mobility Management function, AMF,the SR comprises information indicating the determined plurality of PDUsessions for which the UP is to be established, wherein the informationindicating the determined plurality of PDU sessions for which the UP isto be established comprises a bitmap, wherein each bit of the bitmapindicates whether a corresponding PDU session of the plurality of PDUsessions requires UP establishment.
 2. The method of claim 1, furthercomprising establishing the UP for one or more of the plurality of PDUsessions.
 3. The method of claim 1, wherein determining the plurality ofPDU sessions for which the UP is to be established is in response to:receiving a paging message comprising one PDU session identificationinformation for identifying one PDU session.
 4. The method of claim 3,further comprising: obtaining from the paging message the one PDUsession identification information.
 5. The method of claim 1, whereindetermining the plurality of PDU sessions comprises determining theplurality of PDU sessions for which the UE has UpLink, UL, UP data tosend to a recipient.
 6. The method of claim 1 further comprisingreceiving a NAS response to the SR indicating with a bitmap one or moreestablished PDU sessions from the plurality of PDU sessions.
 7. Acomputer program product comprising a non-transitory storage mediumincluding program code to be executed by processing circuitry of a userequipment, UE, whereby execution of the program code causes the UE toperform operations comprising: determining a plurality of Protocol DataUnit, PDU, sessions for which a User Plane, UP, is to be established;transmitting a Non Access Stratum (NAS) Service Request (SR) to anAccess and Mobility Management function, AMF, the SR comprisesinformation indicating the determined plurality of PDU sessions forwhich the UP is to be established, wherein the information indicatingthe determined plurality of PDU sessions for which the UP is to beestablished comprises a bitmap, wherein each bit of the bitmap indicateswhether a corresponding PDU session of the plurality of PDU sessionsrequires UP establishment.
 8. The computer program of claim 7, whereinthe non-transitory storage medium includes further program code, wherebyexecution of the further program codes causes the UE to perform furtheroperations comprising: establishing the UP for one or more of theplurality of PDU sessions.
 9. The computer program of claim 7, whereindetermining the plurality of PDU sessions for which the UP is to beestablished is in response to: receiving a paging message comprising onePDU session identification information for identifying one PDU session.10. The computer program of claim 9, wherein the non-transitory storagemedium includes further program code, whereby execution of the furtherprogram codes causes the UE to perform further operations comprising:obtaining from the paging message the one PDU session identificationinformation.
 11. The computer program of claim 7, wherein determiningthe plurality of PDU sessions comprises determining the plurality of PDUsessions for which the UE has UpLink, UL, UP data to send to arecipient.
 12. The computer program of claim 7, wherein thenon-transitory storage medium includes further program code, wherebyexecution of the further program codes causes the UE to perform furtheroperations comprising receiving a NAS response to the SR indicating witha bitmap one or more established PDU sessions from the plurality of PDUsessions.
 13. A user equipment, UE, the UE being adapted to: determine aplurality of Protocol Data Unit, PDU, sessions for which a User Plane,UP, is to be established; transmit a Non Access Stratum (NAS) ServiceRequest (SR) to an Access and Mobility Management function, AMF, the SRcomprises information indicating the determined plurality of PDUsessions for which the UP is to be established, wherein the informationindicates the determined plurality of PDU sessions for which the UP isto be established comprises a bitmap, wherein each bit of the bitmapindicates whether a corresponding PDU session of the plurality of PDUsessions requires UP establishment.
 14. The UE of claim 13, furtheradapted to establish the UP for one or more of the plurality of PDUsessions.
 15. The UE of claim 13, further adapted to determine theplurality of PDU sessions for which the UP is to be established inresponse to receiving a paging message comprising one PDU sessionidentification information for identifying one PDU session.
 16. The UEof claim 15, further adapted to obtain from the paging message the onePDU session identification information.
 17. The UE of claim 13, wherein,to determine the plurality of PDU sessions, the UE is further adapted todetermine the plurality of PDU sessions for which the UE has UpLink, UL,UP data to send to a recipient.
 18. The UE of claim 13, wherein, the UEis further adapted to receive a NAS response to the SR indicating with abitmap one or more established PDU sessions from the plurality of PDUsessions.